<?php

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 *
 *	   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * @package log4php
 */

/**
 * This class is specialized in retrieving loggers by name and also maintaining
 * the logger hierarchy.
 * The logger hierarchy is dealing with the several Log-Levels
 * Logger can have. From log4j website:
 *
 * "A logger is said to be an ancestor of another logger if its name followed
 * by a dot is a prefix of the descendant logger name. A logger is said to be
 * a parent of a child logger if there are no ancestors between itself and the
 * descendant logger."
 *
 * Child Loggers do inherit their Log-Levels from their Ancestors. They can
 * increase their Log-Level compared to their Ancestors, but they cannot
 * decrease it.
 *
 * <p>The casual user does not have to deal with this class directly.</p>
 *
 * <p>The structure of the logger hierarchy is maintained by the
 * getLogger method. The hierarchy is such that children link
 * to their parent but parents do not have any pointers to their
 * children. Moreover, loggers can be instantiated in any order, in
 * particular descendant before ancestor.</p>
 *
 * <p>In case a descendant is created before a particular ancestor,
 * then it creates a provision node for the ancestor and adds itself
 * to the provision node. Other descendants of the same ancestor add
 * themselves to the previously created provision node.</p>
 *
 * @version $Revision: 1394956 $
 * @package log4php
 */
class LoggerHierarchy
{

    /**
     * Array holding all Logger instances.
     */
    protected $loggers = array();

    /**
     * The root logger.
     *
     * @var RootLogger
     */
    protected $root;

    /**
     * The logger renderer map.
     *
     * @var LoggerRendererMap
     */
    protected $rendererMap;

    /**
     * Main level threshold.
     * Events with lower level will not be logged by any
     * logger, regardless of it's configuration.
     *
     * @var LoggerLevel
     */
    protected $threshold;

    /**
     * Creates a new logger hierarchy.
     *
     * @param LoggerRoot $root
     *            The root logger.
     */
    public function __construct(LoggerRoot $root)
    {
        $this->root = $root;
        $this->setThreshold(LoggerLevel::getLevelAll());
        $this->rendererMap = new LoggerRendererMap();
    }

    /**
     * Clears all loggers.
     */
    public function clear()
    {
        $this->loggers = array();
    }

    /**
     * Check if the named logger exists in the hierarchy.
     *
     * @param string $name            
     * @return boolean
     */
    public function exists($name)
    {
        return isset($this->loggers[$name]);
    }

    /**
     * Returns all the currently defined loggers in this hierarchy as an array.
     *
     * @return array
     */
    public function getCurrentLoggers()
    {
        return array_values($this->loggers);
    }

    /**
     * Returns a named logger instance logger.
     * If it doesn't exist, one is created.
     *
     * @param string $name
     *            Logger name
     * @return Logger Logger instance.
     */
    public function getLogger($name)
    {
        if (! isset($this->loggers[$name])) {
            $logger = new Logger($name);
            
            $nodes = explode('.', $name);
            $firstNode = array_shift($nodes);
            
            // if name is not a first node but another first node is their
            if ($firstNode != $name and isset($this->loggers[$firstNode])) {
                $logger->setParent($this->loggers[$firstNode]);
            } else {
                // if there is no father, set root logger as father
                $logger->setParent($this->root);
            }
            
            // if there are more nodes than one
            if (count($nodes) > 0) {
                // find parent node
                foreach ($nodes as $node) {
                    $parentNode = "$firstNode.$node";
                    if (isset($this->loggers[$parentNode]) and $parentNode != $name) {
                        $logger->setParent($this->loggers[$parentNode]);
                    }
                    $firstNode .= ".$node";
                }
            }
            
            $this->loggers[$name] = $logger;
        }
        
        return $this->loggers[$name];
    }

    /**
     * Returns the logger renderer map.
     *
     * @return LoggerRendererMap
     */
    public function getRendererMap()
    {
        return $this->rendererMap;
    }

    /**
     * Returns the root logger.
     *
     * @return LoggerRoot
     */
    public function getRootLogger()
    {
        return $this->root;
    }

    /**
     * Returns the main threshold level.
     *
     * @return LoggerLevel
     */
    public function getThreshold()
    {
        return $this->threshold;
    }

    /**
     * Returns true if the hierarchy is disabled for given log level and false
     * otherwise.
     *
     * @return boolean
     */
    public function isDisabled(LoggerLevel $level)
    {
        return ($this->threshold->toInt() > $level->toInt());
    }

    /**
     * Reset all values contained in this hierarchy instance to their
     * default.
     *
     *
     * This removes all appenders from all loggers, sets
     * the level of all non-root loggers to <i>null</i>,
     * sets their additivity flag to <i>true</i> and sets the level
     * of the root logger to {@link LOGGER_LEVEL_DEBUG}.
     *
     * <p>Existing loggers are not removed. They are just reset.
     *
     * <p>This method should be used sparingly and with care as it will
     * block all logging until it is completed.</p>
     */
    public function resetConfiguration()
    {
        $root = $this->getRootLogger();
        
        $root->setLevel(LoggerLevel::getLevelDebug());
        $this->setThreshold(LoggerLevel::getLevelAll());
        $this->shutDown();
        
        foreach ($this->loggers as $logger) {
            $logger->setLevel(null);
            $logger->setAdditivity(true);
            $logger->removeAllAppenders();
        }
        
        $this->rendererMap->reset();
        LoggerAppenderPool::clear();
    }

    /**
     * Sets the main threshold level.
     *
     * @param LoggerLevel $l            
     */
    public function setThreshold(LoggerLevel $threshold)
    {
        $this->threshold = $threshold;
    }

    /**
     * Shutting down a hierarchy will <i>safely</i> close and remove
     * all appenders in all loggers including the root logger.
     *
     * The shutdown method is careful to close nested
     * appenders before closing regular appenders. This is allows
     * configurations where a regular appender is attached to a logger
     * and again to a nested appender.
     *
     * @todo Check if the last paragraph is correct.
     */
    public function shutdown()
    {
        $this->root->removeAllAppenders();
        
        foreach ($this->loggers as $logger) {
            $logger->removeAllAppenders();
        }
    }

    /**
     * Prints the current Logger hierarchy tree.
     * Useful for debugging.
     */
    public function printHierarchy()
    {
        $this->printHierarchyInner($this->getRootLogger(), 0);
    }

    private function printHierarchyInner(Logger $current, $level)
    {
        for ($i = 0; $i < $level; $i ++) {
            echo ($i == $level - 1) ? "|--" : "|  ";
        }
        echo $current->getName() . "\n";
        
        foreach ($this->loggers as $logger) {
            if ($logger->getParent() == $current) {
                $this->printHierarchyInner($logger, $level + 1);
            }
        }
    }
} 
